To explore the influence law of rainfall infiltration on widening deformation in loess subgrade, and reveal the deformation differences between loess widened subgrade and general subgrade under the action of rainfall infiltration. This paper takes typical loess subgrade and widened loess subgrade as the research object, and the centrifuge test model was established to study the deformations of typical loess subgrade and widened loess subgrade under the condition of rainfall infiltration. The changes was monitored for water content and soil pressure inside the two subgrades. The results showed that the settlement deformation was the largest at the top surface center position for the typical loess subgrade under the action of rainfall infiltration, while the settlement deformation at the shoulder was the largest for the widened subgrade. With the increase of rainfall, the increasing extent of deformation gradually decreased. The foundation at the slope foot of widened subgrade was uplifted and deformed, and the central position of subgrade slope was invaginated.There was a dynamic equilibrium process of water content in subgrade, which affects the overall deformation of subgrade.